Method of and apparatus for measuring the composition of gas



March 16, 1948. R. A. ACKLEY I 2,437,720

METHOD OF AND APPARATUS FOR MEASURING THE COMPOSITION OF GAS Filed 'June 14, 1943 Inventor I Robert A.Ack1e y IMMM M Attorneys their respective pressures combustion occurs.

ems radars I vile-mesons APPARATUS non MEAS- -{URING 'IIIE COMPOSITION OF GAS Robert A; seiner. Chicago, n1., assig'nor to RepublioyFlowiMeterl Company, Chicago, 111., a

corporation oi Illinois Application June 14. 1943. semi No. 490,136

This invention relates to method or and apparatus for measuring the composition or gas and more particularly to the measurement of 'the oxygen content of a gas. 1

Heretoiore gas; such' as flue gas or' engine exhaust gas, has been analyzed inan Orsat apparatus which is slow and cumbersome to operate and which does not give a continuous-or instantaneousindication of the composition. v

One of the principal objects of the present invention is to obtain an instantaneous and continuous indication of the composition of a gas by observing the flame temperature produced by burning a mixture of the gas with a combustible. Another object is to provide a method'and apparatus for measuring the composition of a as in which variations in flame. size do not at.- fect the measurement.

Still another object is to compensate for variatlons in the combustible supply: f

The above and other objects and advantages of the invention will be more readilyapparent.

from the following description when-read in connection with the accompanying drawing, in which- Figure 1 is a diagrammatic side'elevationlwith parts broken away illustrating one apparatus for carrying out the invention;

Figure 2 is a similar view ofalternative apparatus: a g

Figure 3 is a partial view similar'to or still another form of apparatus; I

Figure 4 is a partial planview otthe apparatus of Figure 3; and i Figure 5 is a view similar to Figure -1 or an ad- Figure 1 ditionai form of apparatus.

- combustible gas will tend to'aspirate thegas to be measured into the burner and the proportions of the two gases canbe controlledby regulating or in any other desired manner.

The mixture of the gases supplied to'the burner burns in a circular flame indicated at |l having in'its interior the usual cone l5 in'which no I have found that the temperature or the flame varies substantially directly with the percentage of oxygen in the sample gas and that a very accurate indication of the oxygen in the sample gas can be obtained by measuring the flame temperature. For this purpose, as shown in Figure 1, a thermocouple I6 is inserted in the flame and is connected to a millivoltmeter II which may be calibrated to read directly in terms oi, percentage of oxygen.

In order to obtain an accurate indication of a the flame temperature regardless of variations in name size, the thermocouple is mounted above,

and out of line with the axis of the tube l0 so that it will lie in the base of the flame adJacent the cone is. With the thermocouple located in this position, variations in the flame size have v substantially no effect on thetemperature indication and an accurate measurement or the oxygen percentage in the. sample gas is obtained without requiring close regulation of the volume of sample gas and combustible gas supplied.

Figure 2 shows another construction similar to that of Figure 1 and parts therein corresponding to like parts in Figure-1 have been designated by the same reference numerals. In this construction, the temperature of the flame is meas-. ured by a resistance element l8 which is mount-' ed above the tube ill to lie around the flame. The element I8 is formed of a material whose resistance changesjin response to changes of temperature and is connected in one leg of a bridge circuit indicated generally at 19 so that the bridge circuit will be unbalanced in response to changes in the resistance l8. Unbalance of the bridge circuit is indicated by a miili voltmeter 2| which can be calibrated to read directly in terms of percentage 01 oxygen in the sample gas.

Still another construction is shown in Figures 3 and 4 in which a curved bimetal strip 22 is anchored at one end at 23 and lies around the flame II The free end of the strip carries a pointer 24 moving over a scale 25 which can be calibrated to indicate directly the percentage of oxygen in the sample. Inthis construction the strip will flex in response to temperature variations to indicate on the scale the percentage oi oxygen in the sample.

Figure 5 illustrates a construction in which compensation is provided for variations in the combustible gas, parts therein corresponding to like parts in Figure 1 being indicated by the same reference numerals. In this construction a second burner 16 is provided supplied with combustible as through a pipe 21 and with air or like flame spectiveiy in the flames l4 and 28. Similar terminalsof thermocouples 3| and 32 are connected by a wire 33 and the other terminals are connected through a millivoltmeter 34. With this circuit thethermocouples are bucking and the millivoltmeter 34 will measure the difference between the voltage generated thereby which is proportional to the difference in the flame temperatures. Thus any variation in the combustible gas will produce a similar variation in the temperature of both flames and the millivoltmeter will be effected only by changes in the temperature of the flame it caused by variations in the oxygen content of the gas sample. It will be understood that similar compensation could be produced using a bridge circuit as shown in Figure 2 or various other measuring or indicating methods.

.While several embodiments of the invention have been shown and described in detail herein, it will be understood that these are illustrative only and are not intended to be taken as a definition of the scope of the invention, reference being had for this purpose to the appended claims.

What is claimed is:

1. The method of measuring the oxygen content of a gas sample which comprises mixing the gas sample with a combustible gas, burning the mixture in air to produce a substantially circular flame, and measuring the temperature of the flame adjacent its base.

2. The method of measuring the oxygen content of a gas sample which comprises mixing the sample with a combustible gas in predetermined proportions, burning the mixture in air to produce a flame, and measuring the temperature of the flame. I

3. The method of measuring the oxygen content of a gas sample which comprises mixing the sample with a combustible gas in predetermined proportions, burning the mixture to produce a flame, burning a mixture of the combustible gas and air to produce a second flame, andmeasuring the diiference in temperatures of the flames.

4. Apparatus for measuring the composition of a gas sample comprisingmeans for mixing the gas sample with a combustible gas, a burner to burn the mixture, a resistance above the burner whose value varies in accordance with variations in temperature, and means to measure the value of the resistance.

5. Apparatus for measuring the composition a gas sample comprising means for mixing the gas sample with a combustible gas, a burner to 4 burn the mixture, a resistance above the burner whose value varies in accordance with variations in temperature, a bridge circuit in which the resistance is connected, and means to measure the unbalance of the bridge circuit.

6. Apparatus for measuring the compositionof a gas sample comprising means for mixing the gas sample with a combustible gas, a burner to burn the mixture, a bimetal strip above the bumer to be responsive to a flame issuing therefrom, and means to indicate the deflection of the strip.

7. Apparatus for measuring the composition of a gas sample comprising means for mixing the gas sample with a combustible gas, a burner to burn the mixture, a second burner to burn a mixture of the combustible and air, and means to measure the difference in temperatures of the flames issuing from the two burners.

8. Apparatus for measuring the composition of a gas comprising a burner tube, means for supplying gas to be measured and a combustible gas to the burner tube in predetermined proportions, and temperature sensitive means mounted above and displaced from the axis of the tube to lie in the base of the flame to respond to changes in the temperature of a flame issuing from the tube.

9. Apparatus for measuring the composition of a gas comprising a burner tube, means for supplying gas to be measured and a combustible gas to the burner tube, a thermocouple above and ad- 'jacent oneside of the tube to lie in the base of a flame issuing therefrom, and means to measure a function of the voltage generated by the thermocouple. I

ROBERT A. ACKLEY.

REFERENCES CITED The following references are of record in the file of this patent: 

